wildwood/doc/Analysis.md

1.  Analysis

    1.  Accounts from the Philosophy of Science

<Towards another chapter. What l want to do is: ,

1\] present the DN account, and it's defenders.

2\] present the conventional response

3\] present the radical response

4\] add some notes of my own, if possible supported by sources, on the
polemic nature of explanation>

This section looks at accounts of explanation culled from the Philosophy
of Science. My reason for starting with this field of study is that
philosophers in this field have a commitment to express their ideas in
strictly formal ways.

Furthermore, the matter of explanation has always been central to the
study \[see e.g. van Fraassen 80, p 92; Nagel 61, p 4\]. Thus it might
be hoped that they would produce a formal account of what constitutes a
good argument. While it is not necessarily the case that what can be
expressed formally will be computationally tractable, a formal statement
of an idea is at least a good start towards computability.

In fact this link between formal statement and computability is what
makes the methodology of Artificial Intelligence such a good tool for
the philosopher. Where a formal description can be encoded into a
computer language in a computationally tractable manner, the computer
programme can be used to evaluate how well the description matches the
phenomenon described, simply by observing how well the computer models
this phenomenon.

1.  1.  Some definitions

In part of the discussion that follows, it will be necessary to use a
shorthand to describe some of the different positions that have been
adopted at one time or A another by philosophers of science. Two
important positions are realism and A empiricism. The positions are only
peripheral to the discussion that follows, but in using them I will
generally follow van Fraassen's usage: by realism, I will mean the view
that “...science aims to find a true description of unobservable
processes that explain the observable ones...” \[van Fraassen '8O page
3\] This view holds that a theory is only adequate if it's description
of the world is correct in the finest detail.

By contrast, by empiricism I shall mean the view that a theory is
adequate provided it gives a correct account of the observable
phenomena. Any underlying mechanism may be postulated, provided that it
accounts for the observable behaviour.

I shall also use another term from the same debate - positivism. I shall
not use this in the precise sense that van Frassen gives it, but in a
looser, more colloquial sense, to define that group of doctrines
(including all realist and most empiricist doctrines) which hold that
there is a real world, and that that real world is accurately reflected
in our perceptions.

1.  1.  Aristotle to Nagel

The Philosophy of Science has had the development of an account of
explanation as one of its central projects since Aristotle. Aristotle's
account of explanation was broadly that an explanation was an argument
which had the explicandum as its consequent. As, to Aristotle, arguments
should be constructed as syllogisms or chains of syllogisms, the correct
explanation in response to 'How do you know that Socrates is mortal?'
would be:

Socrates is a man;

All men are mortal;

Therefore Socrates is mortal.

\[a syllogism of the mood barbara \]

This account, which has become known as the 'hypothetico-deductive' or
'deductive-nomological' account of explanation, has effectively been the
dominant account ever since. The classic statement of this account in
the present century is probably that given by Hempel \[Hempel, 65\].
Ernest Nagel \[Nagel, 61\] attempted to go beyond this to a more general
account of explanation, but he included the deductive-nomological form
as the first of the four types of explanation which he describes.

Nagel claims, rather baldly, that “Explanations are answers to the
question 'Why?'”, but later goes on to note "...the important point that
even answers to the limited class of questions introduced by 'Why' are
not all of the same kind." His four types of explanation are: deductive
explanations, probabilistic explanations, functional or teleological
explanations, and genetic explanations.

1.  1.  1.  Deductive explanations

Nagel's deductive explanations have the formal structure of a deductive
argument, rather in the manner of a logical proof. This is essentially
the deductive nomological explanation. In the case of the explanation of
singularities, it fits neatly with the Toulmin \[below\] - or indeed the
sylogistic - form of argument: data, plus principle, imply conclusion:

"It is evident that at least one of the premises in a deductive
explanation of a singular explicandum must be a universal law..." (page
31)

"... a deductive scientific explanation, whose explicandum is the
occurance of some event or the possession of some property by a given
object, must satisfy two logical conditions. The premises must include
at least one universal law, whose inclusion is essential to the
deduction of the explicandum. And the premises must also contain a
suitable number of initial conditions." (page 32)

In the case of the explanation of scientific laws, however:

"...all the premises are universal statements; (and) there is more than
one premise, each of which is essential in the derivation of the
exp1icandum..." (page 34)

"...at least one of the premises must be 'more general' than the law
being explained." (page 37)

 The notion of 'more general' is discussed at length, and is defined as
follows:

"Let L~1~ be a law (or a set of laws and theories constituting some
science such as physics), and let 'P~1~' 'P~2~' . . . , 'P~n~' be a set
of 'primitive' predicates in terms of which the predicates occuring in
L~1~ are in some sense definable. (For the sake of simplicity, and
without any loss of the generality of statement, we shall assume that
the predicates are all adjectives or 'one-place' predicates such as
'rigid' or 'heavy' .... ) Similarly, let 'Q~1~' 'Q~2~' . . . , 'Q~n~' be
the corresponding set of primitives for a law L~2~. Finally, let K be a
class of objects, each of which can be significantly (or meaningfully)
characterised, whether truly or falsely, by the predicates of either set
.... We shall also say that an object in K satisfies a law L
'non-vacuously' only if the object actually possesses the various traits
mentioned in the law and, moreover, the traits do stand to each other in
the relations asserted by the law...

We now assume the following conditions: (1) Some (and perhaps all) of
the predicates in the first set occur in the second, but some predicates
in the second set do not occur in the first set. (2) Every object in K
has at least one P-property, that is, a property designated by a
predicate in the first set. (3) There is a non-empty subclass A of
objects in K possessing only P-properties. (4) There is a non-empty
subclass ~~A~~ of objects in K each of which possesses at least one Q-
property that is not a P-property. .... (5) There is a non-empty (but
not necessarily proper) subclass B of objects in K each of which
satisfies L~1~ non-vacuously, and such that some objects in B belong to
A while others belong to ~~A~~. .... (6) There is a non-empty subclass C
of objects in A for which L~2~ holds non-vacuously, and such that some
(and perhaps all) of the objects in C also belong to B ..... When these
six conditions are fulfilled, L~1~ may be said to be more general in K
than L~2~." (pp 40- 41).

\[my transcription differs from the original in. that where Nagel uses a
character formed of an upper case letter A with a bar over it, I have
used a struck-through A; and, more significantly, Nagel uses an unbarred
A in condition 4. From my understanding of the text I have assumed this
is a misprint, and have substituted an struck-through A\]

Deductive explanations, as stated above, have the general form of the
syllogism Barbara. However, Nagel adds a condition: while all the
clauses of Barbara are universally quantified, one of the premisses must
be more general than the conclusion to qualify as an explanation of it.
In the case of an explanation about a singularity, it is trivial that
the 'universal law' is more general than the 'initial conditions'; in
the case of explanations of generalities, Nagel has gone to lengths to
assert this condition.

Nagel rejects as too strong the Aristotelian requirements that the
premises of a deductive explanation should not only be true but should
be *known* to be true, and that they should be ‘better known' than the
explicandum. He observes that the 'universal premises' which are
subsumed into 'scientific laws' are true. Instead he suplies the weaker
condition that:

"...the explanatory premises be compatible with established empirical
facts and be in addition 'adequately supported' (or 'made probable') by
evidence based on data other than the observational data upon which the
acceptance of the explicandum is based." (p 43)

"In maintaining that the premises in an explanation must be 'better
known' than the explicandum, Aristotle was thus simply making explicit
his conception of science. This conception is true of nothing that can
be identified as part of the asserted content of modern empirical
science," (p 45)

1.  1.  1.  Probabilistic explanations

Nagel's second category, probabilistic explanations, depend not on
formal

implication of the explicandum by the premises contained within the
explanation,

but on some 'statistical reregularity' taking the general form:

Most x are y

a is x

=> it is probable that a is y

Nagel notes that:

"It is still an unsettled question whether an explanation must contain a
statistical assumption in order to be a probabilistic one, or whether
nonstatistical premises may make an explicandum 'probable' in some
nonstatistical sense of the word." (p 23)

such explanations can be expressed in the Toulmin scheme (see below);
but as syllogisms have the general form IAA, which is not valid.

These two types are the models of scientific explanation that Nagel
describes; but he also describes two other categories. These are
explanation types which appear in natural conversation, and in law and
the humanities.

1.  1.  1.  Functional (teleological) explanations

Functional (teleological) explanations are explanations which refer to
the supposed purpose of the explicandum:

"lt is characteristic of functional explanations that they employ such
typical locutions as 'in order that', 'for the sake of' and the like."
(p 24)

There are two sub classes of functional explanation. One is the
explanation of a particular instance or occurrence: .. .

'I caught hold of the branch so that I would not fall.'

whereas the other explains something which occurs in all instances of a
particular class:

'Birds have wings so that they can fly.'

1.  1.  1.  Genetic explanations

Genetic explanations seek to explain why something is the way it is by
explaining how it came to be this way:

'My arm is broken because I fell out of a tree'

'Penguins have wings because they evolved from birds which could fly'

It is clear that these are categories where the explanations are neither
necessary nor sufficient causes of the explicanda; you don't have to
fall out of a tree to break your arm, and you can break it without
falling out. Likewise, there may have been other ways of not falling
than catching hold of a branch, and catching hold of a branch may not
prevent a fall.

 But there are statistical probabilities (not necessarily high) that
catching the branch will prevent the fall, and that a fall will lead to
a broken arm.

"It is therefore a reasonable conclusion that genetic explanations are
by and large probabilistic." (p 26)

1.  1.  The radical critics

These conventional arguments in the philosophy of science were
dramatically disturbed in the 1960s by radical philosophers like Thomas
Kuhn \[Kuhn, 62\] and Paul Feyerabend \[Feyerabend, 78; and passim\].
Their attack was not directed specifically at accounts of explanation,
but at the empiricist and realist views of science as such - which is to
say the view – implicit in both – that we can directly access the
external world in order to gain knowledge which would support a theory.

The damage to the account of explanation was almost incidental in this
process. It was fatal, however; the consensual view of explanation did
not survive. A number of accounts of explanation have developed since
then; dissapointingly, these all seem to be timid and conservative,
attempting to preserve a view of science which is no longer tenable.
Following (but not, as far as I am aware, prior to) the radicals
onslaught, writers on the philosophy of science developed a formidable
arsenal of objections to the deductive-nomological account. I cite here
a few drawn from \[Korner 75\]:

Achinstein, in his note The Object of Explanation, gives some 'standard
counler—examp|es':

"1\] We see a fire engine which is black and demand an explanation. Here
is one that satisfies the D-N model:

This fire engine is the same colour as that crow.

All crows are black.

=>This fire engine is black.

2\] A bridge collapses and we demand an explanation, Here is one that
satisfies the D-N model:

An engineer with years of training and experience examined the bridge
and said it would collapse.

Whenever an engineer with years of training and experience examines a
bridge and says it will collapse, it does.

=> The bridge collapsed.

These are unacceptable as explanations .... " (page 35)

Hesse, in her rejoinder to Achinstein, writes:

 “... there are by now at least three widely accepted general
consequences of the ensuing debate which are enough to show that this
model is by no means to be taken as the 'standard model of explanation'.

These are:

(i) It has grave shortcomings as an explication of the structure of
    explanation in natural science itself.
(ii) The question of whether it usefully applies to explanation in
    history, psychology, and the social sciences is a matter of current
    controversy.
(iii)  The question of whether *any* model applying to the natural
    sciences is adequate also for these human sciences is also highly
    controversial." (page 46, Hesse's emphasis)

and finally, Salmon, in a piece entitled Theoretical Explanation,
argues:

"... contra Hempel and many others - that an explanation \[of a
particular event\] is not 'an argument to the effect that the event to
be explained was to be expected by reason of certain explanatory
facts'...

In addition, I have claimed that the so-called deductive- nomological
model of explanation of particular events is incorrect. It is not merely
that there are explanandum events which seem explainable only
inductively or statistically... There are also cases – such as the man
who takes his wife's birth control pills and avoids pregnancy – in which
an obviously defective explanation fulfills the conditions for
deductive-nomological explanation. (pp 118-119; the embedded quote is
from Hempel, Explanation in Science and in History, in Colodny, ed,
Frontiers of Science and Philosophy, University of Pittsburgh Press,
Pittsburgh, 1962. The italics are Salmon's. This birth control example
is also mentioned in for example van Frassen 1980)

\[Here insert some detailed analysis of Feyerabend's position, and
passing reference to Lakatos and Kuhn\]

1.  1.  Achinstein

One of the first attempts to recover an account of explanation from this
mess is that of Achinstein \[Achinstein 83\]. Achinstein distinguishes
between the act of explaining, which is an utterance, and the
explanation, which is the product of the act. This act must take place
in an appropriate context.

His project is to answer three questions: .

1.  What is an explaining act?
2.  What is the product of an explaining act?
3.  How should explanations be evaluated?

<!-- -->

1.  1.  1.  'Explaining acts'

Achinstein claims that 'explaining acts' have a period, and a completion
point.

'John was explaining why x'

'John explained x'

The latter form implies a completion has occurred.

An explanation has not occurred until the act of explanation has
occurred. For John to have explained why x, it is not sufficient that he
knew why x.

'Explaining' is illocutionary \[see Austin, how to do things with
words\]; it is done in an appropriate context. Out of such a context,
the same statement would be an equivalent perlocutary act:
'enlightening', 'getting &lt;the auditor&gt; to understand'.

The intention of an explaining act must be to engender understanding of
the explicanda. Achinstein does not state, but may be taken to imply,
that for such an act to take place there must (at any rate in the mind
of the explainer) be some explainee or auditor, in whose mind
understanding is to be engendered[^1].

"The first condition expresses what I take to be a fundamental
relationship between explaining and understanding. It is that S explains
q by uttering u only if

\(1) S utters u with the intention that his utterance of u render q
understandable."(Page ??) 

Under this account it is impossible to explain something by accident – a
rather over strict condition, l think.

Achinstein also claims that it is neccesary that the utterance produced
by the explaining act must be (at least believed to be) a correct
account:

"(2) S believes that u expresses a proposition that is a correct answer
to Q...

Often people will present hints, clues, or instructions which do not
themselves answer the questions... Some hints, no doubt, border on being
answers to the question. But in those cases where they do not, it is not
completely appropriate to speak of explaining."(p 17)

Thus explanation by analogy is no explanation; again, this seems a very
strong condition. Yet Achinstein goes on to make this even stronger by
the assertion that the proposition expressed by u is itself a complete
answer to Q:

"(3) S utters u with the intention that his utterance render q
understandable by producing the knowledge, of the proposition expressed
by u, that it is a correct answer to Q."(p 18)

Atchinstein goes on to say that 'explain' can be used in two senses: a
loose sense, in which any situation fulfilling the above contains an
explanation; and a more restricted sense, which will "cover only correct
explainings". He does not describe how these may be differentiated,
however.

1.  1.  1.  Understanding

If explaining is to be seen as an act directed at engendering
understanding, some account of what is meant by 'understanding' must be
supplied. Achinstein asserts that:

"One understands q only if one knows a correct answer to Q which one
knows to be correct (sic)... we can say that a necessary condition for
the truth of sentences of the form 'At understands q' is

\(1) (£x)(A knows of x that it is a correct answer to Q)" (p 23 - 4) 

Achinstein's essential problem is quite simple to express: he wants to
say that one doesn't understand something until one not only knows a
proposition which expresses the reason for it, and knows that this
proposition does in fact express the 'correct' reason, but also has
internalised this proposition.

1.  1.  1.  1.  'Content-giving Propositions'

Achinstein identifies a class of nouns which he describes as
'content-giving', such as 'explanation', 'meaning', 'fact', 'reason'. He
then defines a class of propositions, constructed using such nouns and
the verb to be, which he calls 'content-giving propositions'. These take
roughly the form:

'the &lt;cg-noun&gt; {that | of | for} &lt;proposition x&gt; is
&lt;proposition y&gt;.'

Achinstein now expands his definition of understanding to:

"(∃p)(A knows of p that it is a correct answer to Q, and p is a complete
content-giving proposition with respect to Q)" (p 42) .

Achinstein examines a number or accounts of the epistemic nature of an
explanation, largely to use them as Aunt Sallies, before presenting his
preferred account. He examines first explanation considered as sentence
and as proposition.

These are rejected for reasons which appear to me quite strange.
Achinstein has trouble with the idea that two sentences can be
differently constructed but have the same meaning. E.g.:

"...since sentence (1) ≠ sentence (2), the explanation of Bill's stomach
ache given by Dr. \_Smith ≠ the explanation of Bill's stomach ache given
by Dr. Robinson, which seems unsatisfactory. Intuitively, both doctors
have given the same explanation..."(p 76)

What Achinstein dearly wants is some Leibnitzian language in which he
can express the semantic content of the sentences. Not having one, it is
not sufficient for him to posit that such a thing must exist; so he
claims that behind every sentence there is a (presumably unique)
proposition, in English. Thus:

"Since sentences (1) and (2) express the same proposition we can
conclude that the explanations given by the doctors are the same."(p 76)

For evidence that the proposition is considered to be unique, see the
bizarre argument presented as the ’Locutionary Force Problem' on p 77.
ln this (by my reading) he claims that:

ix if the product of an explanation is a proposition, and it is possible
to produce, as separate acts of explanation and of criticism, utterances
which map onto the same proposition, then that proposition is at once a
criticism and an explanation, which is absurd. Therefore the product of
an explanation cannot be a proposition.

l doubt whether this argument has meaning, let alone force. ln this and
other arguments, Achinstein seems to confound operations which would be
legitimate on some formal grammar with what it is possible to do with
natural language.

His view that propositions are unique is made more difficult to maintain
by his apparent identification of the propositions themselves with the
sequence of symbols used to represent it. For a statement of the view
that sequences of symbols are efficient (i.e. that they may have many
differing meanings), see e.g. \[Barwise and Perry 86, p S2\]; ,

He also has trouble with emphasis shifts in propositions which are

represented by the same sequence of word-tokens, which he resolves by
the

concept of 'e-sentences' - sentences with additional flagging to
indicate the

central phrase, so that:

"(7) the e-sentence 'Bill ate spoiled meat on Tuesday' is not

identical with

8 (8) the e-sentence 'Bill ate spoiled meat on Tuesday"' (p 80)

He next considers the deductive-nomological view - the view that an

' explanation is an argument.

Achinstein argues that the form of the deductive nomological explanation
can

be seen as an ordered pair &lt;conjunction of premises, conclusion&gt;.
This view is

dismissed for reasons analogous to those above.

Explanation as ordered pair

Having considered, and dismissed, the preceding accounts of explanation,
A.

\_ now proposes that explanation should be considered to be an ordered
pair &lt;x, y&gt;

s.t.: .

"'The explanation of q given by S denotes (x; y) if and only if

\(i) Q is a content-question; 

\(ii) x is a complete content-giving proposition with respect to Q; 

\(iii) y = explaining q; \` 

\(iv) (£a)(£u)\[a is an act in which S explained q by uttering u -&gt; 

(r)(r is associated with with a;r=x)\]. (i.e., x is the one and only

A proposition associated with every act in which S explained q by \`

uttering something.)"(p 87) \_

What this appears to boil down to is this:

Achinstein believes any given concatenation of symbols representing a

" proposition to be identical with that proposition; and that any
proposition is

uniquel. ·

Thus each and every occurance of this sequence of symbols is the same
thing.

Yet he believes, as shown above, that it is impossible for (e.g.) an
explanation to

lln fact, Achinstein's claim is even stronger than this, for he believes
that there is some

proposition 'underneath' each sentence; thus, potentially, many
sentences may map onto

the same proposition, and consequently all these sentences may be
treated as being

identical (l).

Simon Brooke: Notes for a thesis entitled Page : 34

Meghaniseq Inference and Explanation Draught dated ; 2\]{§\[§§

be 'the same thing' as (e.g.) a criticism. So it is impossible for an
explanation to

be identical with an occurance of a sequence of symbols.

Thus an ordered pair must be constructed, in which the symbol-sequence
is

linked with another symbol sequence which represents a reference to the

question which was asked.

Note that q, the question, is also a sequence of symbols; so that a
pair:

&lt;\[aI| plants are green\]; \[answering: "why is this grass
green"\]&gt; .

is unique, and is always the same explanation. Therefore (since
Achinstein'S4» gp

schema makes no mention of an auditor) it is always either a good
explanation or

a bad one, regardless of whether the question was asked by a three year
old child

or a plant physiologist.

I would like to return the readers attention to Achinstein's claim that:

"One understands q only if one knows a correct answer to Q which

one knows to be correct " \[p 23, my emphasis\]

and goes on to clarify that, by this, he implies '...a de re sense of
knowing.' as

" The use of 'correct' here is the problem. It appears to imply that one
knows that

the answer which one knows maps in some unproblematic way onto something

real in the external world. Thus Achinstein, too, falls into the trap
sprung by the

radicals. ln the absence of some definition of what is to be understood
by

'correct', these definitions are simply meaningless.

 ·; ; —• ·\_ gt g J; rg FQ :r. ns .· efbr ¢'&lt;—¤ · S = " . \~w’ ll’

9 (v x \~ J · 'Q\~ k. , l 6 4 4

P7 » %‘· both orde al ;/ an ns (parables s ve.

‘ This account does not address many of the facets of common sense
explanation.

It has nothing to say about the amount of detail contained in an
explanation. It has

nothing to say about the need to express an explanation in terms of an
account of

the world which is accessible to the auditor. lt fails to account for
the possibility

of explanation by analogy, or of unintentional explanation.

It appears that Achinstein's motivation in producing a new account has
less to

do with addressing these real world problems than with overcoming such

philosophical puzzles as the Paradox of the Ravens; so his account takes
us no

nearer to providing a model which will support the construction of
better

common sense explanations. 5

A \[ mh L/Go/w%\` \\

\` Eegozi

van Fraassen Arclltuqrfélv

\_ Another philosopher who has attracted attention with his work on
explanation

in recent years is Bas van Fraassen. His work seems MNMW directed,
trbeislz

however, not primarily at providing better accounts of explanation, so
much as

at defending the empirical view of science from the realist critics of
it - surely,

at this late date, a redundant activity. The work is marred, in my
opinion, by

intellectually dishonest treatment of the radicals, to whom van Fraassen
has no

honest response.

van Fraassen's response to the radicals

van Fraassen published his ‘the Scientific Image' in 1980, in the age of

Feyerabend and Kuhn. He mentions both these authors twice, and is
clearly

familiar with their theses, describing Feyerabend's work as 'well known'
(page

Simon Brooke: Notes for a thesis entitled Page : 35

l· 1¤ ·•I f I‘ · - • sustai n !q.u •q·• •\$€

14), and paraphrasing one of Feyerabend's central points (although
without

acknowledging it): l

"... one theory says that there are electrons, and the other says that

there may not be. Even if the observable phenomena are as Rutherford

says, the unobservable may be different. However, the positivists

would say, if you argue that way, you automatically become a prey to

scepticism. You will have to admit that there are possibilities that you

cannot prove or disprove by experiment, and so you will have to say we

cannot know what the world is like. Worse; you will have no reason to

reject any number of outlandish possibilities; demons, witchcraft,

hidden powers contirbuting to fantastic ends." (page 35, my emphasis)

Well yes, precisely. And although it is possible that the positivists
would say

it, Feyerabend did say it, repeatedly; and the choice of words seems to
me to

betray a consciousness of this \[see for example Feyerabend, 81, vol 1,
foot of

page 196 - which other evidence (below) shows us van Fraassen was
familiar

with\]. But the only time van Fraassen addresses an argument of
Feyerabend's

directly, he dismisses it as '...a totally false issue...' (page 93).
Let us look a

P little at the context for this. 3

van Fraassen is discussing the centrality of explanation to science,
citing -

and accepting - Nagel's strong claim \[Nagel 61, page 4\], and using
incidentally

the same passage from Nagel as Feyerabend had used in his earlier
critique of this

work \[Feyerabend 81, page 52; this paper originally published in BJPS
vol 16,

1964\] to illustrate this. He claims that Nagel's view does not entail
realism, but

will equally support an empiricist view. He now claims that Feyerabend
has

advanced the '..totally false..' argument that, in his paraphrase:

'...only Realism is a philosophy that stimulates scientific enquiry;

anti-realism hampers it." \[page 93\]

This is a position that Feyerabend advanced? Really? Feyerabend whose

central thesis might be summed up in his phrase "The only principle that
does

not inhibit progress is: anything goes." \[Feyerabend 75, p10: F's
emphasis\]. van

Fraassen refers us to Feyerabend's paper \[in

Feyerabend 81 vol 1\]. What Feyerabend in fact says (forgive me ifi
quote at

length) is:

"To sum up: the issue between realism and instrumentalism has g\`

A many facets..... There are arguments for instrumentalism which

concern specific theories such as the quantum theory or the

heliocentric hypothesis and which are based on specific facts and well

confirmed theories. It was shown that to demand realism in these cases

\* amounts to demanding support for implausible conjectures which

possess no independent empirical support and which are inconsistent

with facts and well confirmed theories. It was also shown that this is a

plausible demand which immediately follows from the principle of

testability. Hence realism is preferable to instrumentalism even in

these most difficult cases." \[Feyerabend 81 vol 1 pp 201-2;

Feyerabend's emphasis.

'Realism is preferable to instrumentalism'. That is a very different
(and far

weaker) claim than 'only Realism stimulates scientific enquiry'. So the

totally false issue is of van Fraassen's own devising, and has nothing
to do with

Feyerabend.

Simon Brooke: Notes for a thesis entitled Page : 36

ll‘ tan ·• l“\`l · anu, ne u lan uw •\$¢

l have gone on at some length about van Fraassen's slight (and
slighting)

mention of Feyerabend. Why? Well, because van Fraassen, continueing the
now

moribund debate between realsim and empiricism in order to defend the
latter,

addresses Feyerabend's criticisms of neither doctrine. This seems an

extraordinary ommission.

&lt;Here insert some stuff about van Fs account of exp/anati0n...&gt;

Toulmin

Turning aside for the moment from those philosophers who have made a
study VcL‘&‘/6

of explanation per se, there is another whose work is currently
attracting

fashionable attention in Expert Systems (and especially mechanised
explanation)

circles; one must make passing reference to Toulmin, and, unless one
chooses to

use his argument schema, one must produce a very good argument for not
doing

so. Therfore it is important to know what he actually argued.

A Tou|min's programme was to replace the syllogistic with a new logical

schema of his own. He did not address symbolic logic except by
dismissing it as

irrelevant to the study of real world arguments:

"We shall have to replace mathematically-idealised logical

relations - timeless context-free relations between either statements

or propositions — by relations which in practical fact are no more than

the statements to which they relate. This is not to say that the

elaborate mathematical systems which constitute 'symbolic logic' must

now be thrown away; but only that people with intellectual capital

invested in them should retain no illusions about the extent of their

relevance to practical arguments." (Toulmin 58, p 185)

or again:

"...the question needs to be pressed, whether this branch of

mathematics (propositional calculus) is entitled to the name 'logical

theory'. If we give it this name, we imply that the propositional

calculus plays a part in the assessment of actual arguments comparable

to that played by physical theory in explaining actual physical

phenomena. But this we have seen reason to doubt: this branch of \~

" mathematics does not form the theoretical part of logic... By now, the

mathematicians logic has become a frozen calculus, having no

functional connection with the canons for assessing the strength and

\_\` cogency of arguments." (Ibid, p 186 - and he goes on in this vein!)

These contentions seem polemical, even propagandistic, in tone; they are

certainly not, in Tou|min‘s own terminology, 'candid'. They advance
scant

evidence in support of their allegations. They seem out of place in a
work whose

matter is the analysis of argument; and they lie especially uneasy with
TouImin's

claim to be seeking to make argument more scrutable.

He goes on to attack the concept of ‘logicaI form' and 'formal validity'
in

argument:

Simon Brooke: Notes for a thesis entitled Page : 37

1: nan ·•. · ·n · an ,...».ent -1 U an u ·•. 1- \$3

"...the suggestion that validity is to be explained in terms of

'formal properties', in any geometric sense, loses its plausibility."

(Ibid, p 120)

He argues that the conception that arguments in general could or should
have a

logical form arises out of a false start in the study of logic:

"The development of logical theory... began historically with the

study of a rather special class of arguments -\_ namely, the class of

unequivocal, analytic, formally valid arguments with a universal

statement as 'major premiss'. Arguments in this class are exceptional

in four different ways, which together make them a bad example for

general study." (Ibid, p 144)

Clearly, if arguments have no logical form, it is not possible to
advance a

decision process for them, and Toulmin does not attempt to do so.
Rather, the

burden of his argument is that decision processes are (for real world
arguments)

impossible in principle.

Thus those practitioners in the field of Expert Systems who advance
Toulmin

,·— as an authority must face up to this corrolary: if Toulmin's
arguments are valid,

then there cannot ever be a successful Expert System based on any
technology we

have now available, as all current Expert Systems are based on some
logical

formalism (even if, as in the case of production systems, this formalism
is

crude); and all, certainly, claim to be decision processes for arguments
in their

domain. As such, according to Toulmin, they are the modern equivalents
of the

PhiIosophers' stone - they cannot exist.

He was, to be fair to him, writing in the year that LISP was being
developed,

when the posibility of mechanical inference was dreamed of only by
visionaries

like Turing; nevertheless the cavalier manner in which he dismisses all
of the

19th and 20th century advances in logic significantly weakens his claims
to be

taken seriously in this field.

But if Toulmin cannot be taken seriously as a logician, is there any
residual

value in his work on argument? I think it is possible that there is,
because the

argument schema with which he hoped to replace both the traditional
syllogism,

and the formalisms of modern logic, does indeed capture the content of
normal

conversational discussion in an easily manageable form. Had Toulmin
advanced

this and this only, I think he might have been taken more seriously; and
I think x

A there is merit in the current revival of interest in it.

the Schema

Toulmin's concern is with arguments as they are presented informally, in

\* conversation or writing, and the relation between the form of such
informal

arguments and the forms recognised by formal logic. \`

He questions whether the aristotelian 'standard form' of an argument is

'candid'; that is, whether it is presented in such a way as to make its
merits as

argument most manifest. He suggests that the analysis into only three
elements,

major premiss, minor premiss, conclusion may be artificially simplified:

"Simplicity is of course a merit, but may it not in this case have

been bought too dearly? Can we properly classify all the elements in

our arguments under the three headings, 'major premiss', 'minor

premiss' and 'conclusion', or are these categories misleadingly few in

Simon Brooke: Notes for a thesis entitled Page : 38

U' al. “! ‘·1 · any t •n |»•1 •qf•. •¢\$

number? Is there even enough similarity between major and minor

premisses for them usefully to be yoked together by the single

name...?"

He draws on the practice of jurisprudence to find alternative schemae;
and

synthesises one such comprising the following elements: a statement of
some

assertion, which implicitly carries with it a g\_|\_a\_j\_m\_ as to the
truth of the

assertion; and data, information which is consensual at the time of
argument (or

is supported by some futher argument), which tends to support that
claim; some

inference rule, a warrant, which will allow the argument to move from
the data

to the claim (for example, 'all as are bs'), again optionally supported
by some

further argument or bagking; an optional ggjalifigr (e.g. 'probably', 'l
believe');

and, implicit in the qualifier, the possibility of a rebuttal:

D —------------··-— &gt; S0, O , C

I I

I I

Since Un/ess

' W F?

I

on account of

B

(after Toulmin, p 104: my emphasis of optional elements)

In conversation, Toulmin argues, it may be natural simply to say
'&lt;data&gt; so

&lt;c|aim&gt;' ; to say '&lt;c|aim&gt; because &lt;warrant&gt; because
&lt;data&gt;' "...strikes us as

cumbrous and artificial, for it\_puts in an extra step which is trivial
and

unnecessary".

Toulmin sets out to validate this schema by comparing it with the
syllogism,

and asking "'What corresponds in the syllogism to our distinction
between data,

warrant, and backing?"' He devotes special attention to arguments of the
forms

'Almost all A's are B's' and 'Scarcely any A's \_are B's' - forms which
are, of

course, of the utmost importance in default logics, but which are beyond
the

scope of the syllogistic. He shows that such arguments are representable
using

his schema without difficulty, and that the traditional syllogism forms
are also so

representable.

f But beyond this he observes that the major premiss of a syllogism
plays a

dual role with hegemonistic implications: it is at once an inference
step and an

assertion of some piece of information. Thus one may challenge it in its
role as

\_; warrant, on the basis that it is not relevant to the case, and as
backing, on the

grounds that it is not true. TouImin's schema, by separating these
roles, makes \` . \_ E

clearer from what grounds a counter argument can be launched. °\_ i.\_
\` \`

While TouImin's ambitious claims for his schema as the authoritative
tt-, . \_ f,

representation of argument - and his audacious dismissal of modern logic
- seem Q\_ A »\_ ·\_ ·

unworthy of attention, his representation shema does offer some merits
in the W ; ‘ \\ M I

representation of real world arguments, especially those which appeal to
default .»—l— .,,\_

reasoning. Furthermore, the fact that these argument structures can be
'daisy-

. chained' offers a convenient way to pack up large arguments into a
structure

which can be unfolded to any given level of detail, and this property
makes the

Simon urookez Notes ror a tnesns emmeo r-age ; eu

· {n w 1.··1· qa .• ·n. •n |·.•n nv . •\$\$

schema an interesting candidate argument representation as we look for
ways to

control the amount of detail revealed to the user of an Expert System.

His contention that argument can be hegemonic is one which I shall want
to

examine further.

Towards a Situation Semantic account of Explanation

Part of Barwise and Perry's programme in constructing Situation
Semantics

was to elucidate the problem of the transfer of knowledge from one
person to

another, and this is, of course, one of the central problems in an
account of

explanation.

However, they give no account of explanation as such. What follows is my

guess at what their account would look like, had they formally stated
it. This

should not be taken too seriously, as their formalism is rich and
complex, and I

have by no means mastered it. Certainly, any howlers in what follows all
my own

work. \`

My first ‘cut’ at the problem looked like this. An explanation was to be
that

which happened in a situation E defined:

° E := at jj: understands, \_a, gg no

understands, p\_, \_c\_; yes

enquirlng, g; yes

addressing, \_a\_, \_b\_; yes

S¤Yl¤9. Q. 9; l/GS

subject, g, g; yes

atlz: responding, bi, g; yes

addressing, \_b\_, a\_; yes

\$¤Yl¤9. 9.. ll; VSS

subject, \_u, jg; yes

atj3: understands, gd, g; yes

understands, p\_, \_c\_; yes \`

I1 \`&lt; lz '&lt;Is

»» where: a, b are some actors; c is some concept; q, u are some
utterances. "

This begs a number of questions. Firstly, what relationship is meant by

’understands, x, y' ? This question is, of course, the central one for
the whole

programme of Situation Semantics; when it can be answered, the programme

\*1 will have succeeded. Secondly, how can we represent the (presumed)
causal

dependence of the understanding at I3 on the responding at I2 ? Thirdly,
what

implications (if any) does this have for the semantic content of u?

However, this definition does have some points of value. Firstly, an

explanation is located in a situation with at least two roles (which,

incidentally, cannot be taken by the same individual); secondly, a
transfer of

understanding takes place. Neither of these points are met by
traditional

accounts.

So what we need to add is something like this. The sage's response, u,
must

be seen as a list of statements \[sq, sg, sn\], Such that, for any
statement sj

Simon Brooke: Notes for a thesis entitled Page : 40

ll: ·.¤ ‘• .|.&lt;·n · aan .•tn» •n |q•1 •··• •\$\$

in u, sj is understandable in terms of \[&lt;students state of knowledge
at l1&gt; + sj

+ + Sl-1\]. and also that c, the concept originally asked about, is

understandable in-terms of \[&lt;students state of knowledge at l1&gt; +
sj + +

sn\]. This (fortunately) accords with Barwise and Perry's understanding:

"An utterance u of a sentence l/I gives us not just one discourse \_

situation d for 1/J that is part of u, but also discourse situations d G
for

every constituent expression 0 of ltr, discourse situations that are
also

parts of u... Thus, part of what the utterance gives us is the set

{d G : cz is zlr or a constituent of lp}

of discourse situations." \[Ibid p 123\]

This is inadequate, because (among other things) it fails to represent
the

negotiation which is inherent in the construction of many real world

explanations.

However, it appears to be a step along a potentially interesting path,
and

one which I intend to pursue.

A lemma eeneerning the natjjre ef pereeptign

The major argument which l wish to develop in this chapter is based on a
very

important - and contentious - assumption: there may (or may not) be such
a thing

as a real world, but it's existance is largely irrelevant, as if it does
exist, we are

unable to percieve it directly. So before going on to advance this major
argument, l

will attempt to support this lemma.

In van Fraassen's words, "the human organism is, from the point of view
of

physics, a certain kind of measuring apparatus. As such, it has certain
inherent

|imitations... " \[van Fraassen 80, p 17\] Precisely: and as van
Fraassen observes,

our perceptions of the world are conditioned by the nature of this
apparatus, and by

these limitations, which, as he goes on to claim, "...wilI be described
in the final

physics and biology." \[ibid\] But how can this be? We are to
investigate the nature of

these instruments, using, as analytic tools, the instruments themselves.

Take for example the human eye. We know what the eye looks like; we've
seen

many of them: with our eyes. We know their physical nature, because
biologists have

dissected them, and using their eyes, have made careful diagrammes of
what they 7;

A have seen, which we, in turn, can examine using our eyes. F \`

So, if our theories about the nature of the eye are right, and it does
indeed

project a two dimensional image of a three dimensional world (supposing
such

at exists) onto our retinas, then our theories about the nature of the
eye are right.

This argument is not as far fetched as it sounds: after all, the memory
of a

computer \[assuming, for the moment, that such things exist\] is
strictly one

dimensional - a vector of cells. Yet Computer-aided design software, for
example, or

flight simulator software, renders an image from this one-dimensional
environment

onto a two dimensional screen in such a way that we interpret it in
three dimensions.

Simon Brooke: Notes for a thesis entitled Page : 41

Meclgegieeg lgteregce egg Explegeticg Qragghtegtegj ·, 21\[§\[§§

If such transformations between a one dimensional reality and a three
dimensional

appearance are possible in a machine, why not in our own optical
systems?1

Furthermore, our theories about the nature of world are conditioned by
the

languages in which we express them. Different languages allow for the
descrition of

different theories about reality. Again, different communities (or even
individuals)

using what they believe to be the same language (say, for example,
English) may

attatch sufficiently different interpretations to the same linguistic
symbols and

constructs that communication fails, without either of the parties being
aware that

it has failed. This point, about the incommensurability of (some)
theories has been

made many times \[see eg Kuhn, Feyerabend\]; but some of the
consequences require

exploration.

An erggment cencerning the netgre cf explgneticn

Firstly, if we cannot access reality except through the medium of
theory, then

Nagel's claim that an explanation is a mapping from a statement to
reality must fall.

It becomes clear that explanation can at best be a mapping from a
statement to a

theory. ls this a good account of the nature of explanation? .

A Well, let us consider what, in common sense, we think of as 'a good
explanation'.

We feel we have recieved a good explanation if we 'understand' both the
explanation

and the explicandum; if it 'makes sense': if, in fact, we do not
percieve it as grossly

inconsistent with the body of 'be|ief' or 'know|edge’ which we already
hold.

For example, most modern Western people would not think that the
statement:

'the God Fla drives his chariot daily across the rainbow bridge'

was a good explanation of why the sun rises and sets; we do not believe
that there

is a God Fla, nor that what we percieve as the sun is identical with
this being, nor

that a rainbow is sufficiently rigid and strong to bear the weight of
such a being,

lThis argument that our perception of a 'real world' does not prove its
existence is not

new, of course. Here is a classic statement of a similar argument from
BerkeIey's Fire;

Dielegge cf Hylee end Philcnegcz

Hyl.: Do we not perceive the stars and moon, for example, to be a

A great way off? Is not this, I say, manifest to the senses? I

Phil.: Do you not in a dream too perceive those or like objects?

Hyl.: I do.

)‘ Phil.: And have they not then the same appearance of distance?

Hyl.: They have.

Phil.: But you do not htence conclude the apparitions in a dream to
q..;F

be without the mind?

Hyl.: By no means.

Phil.: You ought not therefore to conclude that sensible objects are

without the mind, from their appearance or manner wherein they are

percieved.

Hyl.: I acknowledge it.

Simon Brooke: Notes for a thesis entitled Page : 42

should it exist. But to a first kingdom Egyptian, it may have been an
excellent

explanation. Similarly, that first kingdom Egyptian would not accept the
statement:

'the Earth rotates on its axis once every day'

as a good explanation for the occurance of the same phenomenon. He would
know

perfectly well that the earth, being fixed, could not rotate on its
axis. And even if it

could, why should this influence the daily ritual of Ra?

We consider an explanation good if it maps a statement about
theexplicandum

onto the theory, or body of belief, which we currently ho|d.1

\[Main text of argument. In the tradition of 'philosophy of science' I
intend to

draw on examples from two genuine debates, drawn in this instance from
the

development of the theory of evolution. These debates are

The debate between Huxley and Kropotkin over whether co-operation or

competition was the more important factor in the survival of species.

Kropotkin, a leading Anarchist, sought to show that human beings (among

other animals) were inherently co-operative, and (implied conclusion)

»· would get along fine in the absence of government. Huxley, a Tory,
sought to

show that, on the contrary, competition (and, implicitly, capitalism)
red in

tooth and claw was 'natural'.

The debate between Bateson and Kammerer over whether aquired

characteristics were inherited.

Kammerer, then the only scientist capable of breeding many species of

amphibian in captivity, showed in a series of experiments that

characteristics aquired by parents were inherited by their offspring.

Bateson, in a series of increasingly virulent attacks, ultimately
claimed that

these experiments were fraudulent. As no-one else was even capable of

breeding the creatures involved, they could not be repeated.

Kammerer was a communist, and the implicit argument behind his work

was that human beings were perfectable; that some parts of the benefits
of

humane education and culture would be transmitted. Bateson was again a
Tory,

though not as politically committed as the other figures discussed.

In these debates it is clear that the protagonists sought ot explain a

phenomenon - in this case evolution - in terms of theories which
supported their \_

» own views of the world. The act of explanation was clearly being used
as a polemic

act, to try to pursuade the explainee of the correctness of the
explainers

ideological stance\]

4\. 

ll am grateful to Vernon Pratt for helping me clarify the consequences
that this doctrine

has for the concepts of 'theory' and 'belief'. lf it is the case that
there is no access to a

'real world', then all statements about the nature of the world are of
equal -

undifferentiable - validity (except in so far as some aesthetic criteria
may be applied to

them). lt remains possible to differentiate between a belief - an
unsupported statement

about the nature of the world - and a theory: a statement that the world
has some

property as a consequence of certain other properties which it may have.
However, it

seems to me that this distinction is of little practical importance.

Simon Brooke: Notes for a thesis entitled Page : 43

li‘ al ,‘! n··n ¢ in L.•-,ni •a |a•1•¤·• •\$¢

Linguistics

Psychology

Referenses:

PhHosophy · V

Barwise, Situations and Attitudes (?)

Feyerapend, Ageinst Metheg

ven Fresssen, B Q: The Seientifis Image: Qlerengen Press, Qxfgrg, 1QSQ

Garfinkel, Forms of Explanation

Nagel, The Structure of Science

Pepper, K Qeniesjures and Refujetiens

A Toulmin, The uses of Argument A

Linguistics

Sperber, Relevance

Psychology

Antaki, Lay Explanations of Behaviour

Craik, The Nature of Explanation

Draper, S W·, A User Qentreg Qeneep\] ef Explenatien: Alvey Exp SIS 2

O'Me||ey, Q: Applying Studies ef Neturel Dielegge te Human Qempggter
Intereejienz Alvey

Exp SIQ 2 \_

Artificial Intelligence . \~

A Goguen, Reasoning and Natural Explanation \`

·k.

[^1]: Later (p 19), Achinstein refers to 'the audience'. By contrast, he
    cites (p 20) an alternative formulation by RJ Mattews in which the
    audience is explicitly represented.